Non-corrosive lubricant compositions



NON-CORROSIVE LUBRICANT COMPOSITIONS Ellis K. Fields, Chicago, 11]., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana I No Drawing. Filed Dec. 6, 1951, Ser. No. 700,981

'18 Claims. 01. 252-321 This invention relates to new compositions of matter having corrosion and oxidation inhibiting properties, and to oleaginous compounds containing such new composi tions of matter which are non-corrosive and resistant to oxidation. More particularly, the present invention is directed to lubricants for internal combustion engines which are resistant to the formation of gums, resinous and varnish-like materials, and which are non-corrosive, particularly to alloy bearings.

Many oils are not well suited as lubricants for use in internal combustion engines, particularly of the type operating under severe operating conditions, since under such severe operating conditions they are susceptible to deterioration resulting in the development of carbonaceous and/orresinous or similar varnish-like deposits in the engine and on and about the valves and rings of the engine. Furthermore, such lubricants are often corrosive, particularly to the alloy hearings in such engines.

It is an object of this invention to provide a new composition of matter which has corrosion and oxidation inhibiting properties. Another object of the present invention is to provide a combination of additives for oleaginous compounds, such as oils, particularly hydrocarbon oils which will stabilize such oils against oxidative deterioration and which will render the oils non-corrosive. Itis another object of the present invention to provide lubri-' cants for internal combustion engines which do not form carbonaceous deposits or resinous varnish-like materials on and about the valves, pistons and rings of such engines. Another object of the invention is to provide a class of additives for lubricating oils which will materially inhibit the formation of carbonaceous deposits and/or resinous varnish-like materials and which will render the lubricants non-corrosive, particularly to metals of the hard metal alloy type, such as cadmium-silver alloys, copper-lead alloys, etc. Other objects and advantages of the invention will become apparent from the following description thereof.

In accordance with the present invention, the foregoing objects can be attained by incorporation in an oleaginous compound, such as a lubricating oil, e.g. a mineral oil, from about 0.01% to about 10% of an oil-soluble reaction product of Z-amino-S-thio-l,3,4-dithiazolidine with an aldehyde and a mercaptan. The reaction product of this invention is suitably obtained by adding the aldehyde to the 2-amino-5-thio-1,3,4-dithiazolidine, stirring at 20- 40 C. for about 10 minutes to about 60 minutes, adding the mercaptan and heating the mixture at a temperature of from about 85 C. to about 140 C. for from about 0.5 hour to about 4 hours. The reaction is preferably car- 2,971,909 Patented Feb. 14, 1961 can be from 1:1:1 respectively to 1:22 respectively.

The Z-amino-S-thio-1,3,4-dithiazolidine has the structural formula The aldehyde employed may be an aliphatic, an aromatic, or a heterocyclic aldehyde of from about 1 to about 20 or more carbon atoms, and may contain substituents, such as alkoxy, hydroxy, alkyl mercapto, halogen or nitro groups. hyde, acetaldehyde, benzaldehyde, 2-ethylhexyl aldehyde, butyraldehyde, heptaldehyde, caprylic aldehyde, acrylicaldehyde, crotonaldehyde, vinyl acetaldehyde, phenyl acetaldehyde, nitrobenzaldehyde, salicyaldehyde, furfural, thiophene Z-carboxaldehyde, chloral, etc. Any mercap tan can be employed in the reaction although an aliphatic or aromatic monoor pOly-mercaptan containing from about 1 to about 30 carbon atoms, and preferably from about 6 to about 20 carbon atoms, is preferred. Examples of suitable mercaptans are ethyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, nonyl mercaptan, octadecyl mercaptan, thiophenol, etc.

The preparation of the above-described reaction products is illustrated by the following examples, which are given by way of illustration and are not intended to limit the scope of the invention. For convenience, the 2- amino-S-thio-l,3,4-dithiazolidine is referred to in the following examples as ADT:

EXAMPLE I To a suspension of 26.8 g. (0.0894 mole) ADT in ml. dioxane was added 30.4 ml. (0.1788 mole) 37.3% aqueous formaldehyde. The mixture was stirred at 30 C. for 30 minutes, treated with 60.8 ml. (0.1788 mole) t-octyl mercaptan, and stirred at 100 C. for 2 hours. The solid all went into solution after 30 minutes. The cooled solution was diluted with ml. hexane and 50 ml. benzene, the hexane layer separated and evaporated in vacuo up to 90 C. at 3 mm. The residue, 67 g. was a clear orange liquid containing 28.8% S and 5.89% N.

Examples of suitable aldehydes are formalde- EXAMPLE IV A mixture of 30 g. (0.2 mole) ADT, 62.5 ml. (0.4 mole) Z-ethyl hexaldehyde, and 100 ml. dioxane was stirred at 30 C. for minutes, treated with 64 ml. (0.4 mole) t-octyl mercaptan, stirred at 100 C. for 2 hours, and stripped in vacuo, The residue was taken up in 200 ml. hexane, filtered, and again stripped in vacuo,

giving 80 g. viscous orange product containing 22.97%

S and 6.53% N.

EXAMPLE V A mixture of 30 g. (0.2 mole) ADT, 80.4 g. (0.4 mole) t-dodecyl mercaptan, and 40.5 ml. (0.4 mole) benzaldehyde was stirred 1 hour at 30 C., 1 hour at 100 C. (all ADT went into solution after 40 minutes), and 1 hour at 120 C. with nitrogen blowing. The mixture was cooled to 30 C. and filtered through celite, giving 95 g. viscous orange oil, containing 16.17% S and 1.67% N.

EXAMPLE VI A mixture of 30 g. (0.2 mole) ADT, 36.8 ml. (0.4 mole) 2-thiophenecarboxaldehyde, and 100 ml. dioxane was stirred at 30 C. for 1 hour, treated with 64 ml. (0.4 mole) t-octyl mercaptan, refluxed 2 hours, then stripped in vacuo. The residue was dissolved in 200 ml. hexane, filtered, and evaporated on the steam bath, giving 85 g. red, viscous liquid, containing 33.08% S and 2.27% N.

The above described reaction products are effective corrosion inhibitors, when used in combination with lubricant base oils, such as hydrocarbon oils, synthetic hydrocarbon oils, such as those obtained by the polymerization of hydrocarbons, such as olefin polymers, for example, polybutenes, polypropylene and mixtures thereof, etc.; synthetic lubricating oils of the alkylene-oxide type, for example, the Ucon oils, marketed by Carbide and Carbon Corporation, as well as other synthetic oils, such as the polycarboxylic acid ester type oils, such as the esters of adipic acid, sebacic acid, maleic acid, azelaic acid, etc.

While the above described reaction products can be suitably employed alone in a base oil, they are usually used in combination with other lubricant addition agents, which impart various desired characteristics to the base oil. Usually, these reaction products are used in conjunction with detergent-type additives, particularly those which contain sulfur or phosphorus and sulfur. The additives of this type are usually used in amounts of from about 0.05% to about 25%, and preferably from about 0.10% to about 10%. Among the phosphorus and sulfur-containing addition agents are the neutralized reaction products of a phosphorus sulfide, a hydrocarbon,- an alcohol, a ketone, an amine or an ester. of the phosphorus sulfide reaction product additives, we prefer to employ the neutralized reaction products of a phosphorus sulfide, such as phosphorus pentasulfide, and a hydrocarbon of the type described in US. 2,316,082 issued to C. M. Loane et al., April 6, 1943. As taught in this patent, the preferred hydrocarbon constituent of the reaction is a mono-olefin hydrocarbon polymer resulting fromthe polymerization of low molecular weight monoolefin hydrocarbons, such as propylenes, butenes, amylenes or copolymers thereof. Such polymers may be ob tained by the polymerization of monoolefins of less than 6 carbon atoms in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, al min m 4 5' chloride, or other similar halide cat'alysts of the Friedel- Crafts type.

The polymers employed are preferably mono-olefin polymers or mixtures of mono-olefin polymers and isomono-olefin polymers having molecular weights ranging from about 150 to about 50,000, or more, and preferably from about 500 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid phase of a hydrocarbon mixture containing monoolefins and isomono-olefins, such as butylene and isobutylene at a temperature of from about 80 F. to about 100 F. in the presence of a metal halide catalyst. of the Friedel-Crafts type, such as for example, boron fluoride, aluminum chloride, and the like. In the preparation of these polymers, a hydrocarbon mixture containing isobutylene, butylenes and butanes recovered from petroleum gases, especially those gases produced in the cracking of petroleum oils in the manufacture of gasoline, can be used.

'Essentially paraffinic hydrocarbons, such as bright stock residuums, lubricating oil distillates, petrolatums, or paraffin waxes may be used. There can also be employed the condensation products of any of the foregoing hydrocarbons, usually through first halogenating the hydrocarbons and then condensing with aromatic hydrocarbons in the presence of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride, and the like.

Examples of other high molecular weight olefinic hy-' drocarbons which can be employed are cetene (C cerotene (C melene (C and mixed high molecular weight alkenes obtained by cracking petroleum oils.

Other hydrocarbons that can be reacted with a phosphorus sulfide are aromatic hydrocarbons, such as for example, benzene, naphthalene, toluene, xylene, diphenyl, and the like, or an alkylated aromatic hydrocarbon, such as for example, benzene having an alkyl substituent having at least four carbon atoms, and preferably at least eight carbon atoms, such as a long chain paraffin wax.

The phosphorus sulfide-hydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide, for example, P 8 with the hydrocarbon at a temperature of from about 200 F. to about 500 F., and preferably from about 200 F. to about 400 F., using from about 1% to about and preferably from about 5% to about 25% of the phosphorus sulfide in the reaction.

It is advantageous to maintain a non-oxidizing atmosphere, such as for example, an atmosphere of nitrogen above the reaction mixture. Usually, it is preferable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary; however, an excess amount of phosphorus sulfide can be used and separated from the product by filtration or by dilution with a hydrocarbon solvent, such as hexane, filtering and subsequently removing the solvent by suitable means, such as by distillation. If desired, the reaction product can be further treated with steam at an elevated temperature of from about F. to about 600' F.

The phosphorus sulfide-hydrocarbon reaction product so obtained is neutralized by treatment with a basic reagent; when neutralized with a basic reagent containing a metal constituent, the final product is characterized by the presence or retention of the metal constituent of the basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the acidic reaction product with a suitable basic compound, such as th hydroxide, carbonate, oxide, or sulfide of an alkaline earth metal or an alkali metal, such as for example, potassium hydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, barium hydroxide, barium oxide, etc. Other basic reagents can be used, such as for example, ammonia or an alkyl or aryl-substituted ammonia, such as amines. The neutralization of the phosphorus sulfidehydrocarbon reaction product is carried out preferably in a non-oxidizing atmosphere by contacting the acidic reaction product either as such or dissolved in a suitable solvent, such as naphtha, with a solution of the basic agent. As an alternative method, the reaction product can be treated with solid alkaline compounds, such as KOH, NaOH, Na CO K CO CaO, BaO, Ba(OH) Na,S, and the like, at an elevated temperature of from about 100 F. to about 600 F. Neutralized reaction products containing a heavy metal constituent such as for example, tin, titanium, aluminum, chromium, cobalt, zinc, iron, and the like, can be obtained by double decomposition and other well known methods.

Other phosphorus sulfide-reaction products which can be used are the reaction products of a phosphorus sulfide and a fatty acid ester of the type described in US. 2,399,- 243; the phosphorus sulfide-degras reaction products of US. 2,413,332; the reaction product of an alkylated phenol with the condensation product of P 8 and turpentine of U.S. 2,409,877 and US. 2,409,878; the reaction product of a phosphorus sulfide and stearonitrile of U.S. 2,416,807; etc.

The effectiveness of the herein described reaction products in respect to inhibiting corrosion of metals, e.g. copper-lead alloy bearing metal, and inhibiting the oxidation of oils is demonstrated by the below tabulated data, obtained by subjecting lubricants containing the additive to the following test:

A copper-lead test specimen is lightly abraided with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The clean copper-lead test specimen is suspended in a steel beaker, cleaned with a hot trisodium phosphate solution, rinsed with water, then acetone, and dried, and 250 grams of the oil to be tested, together with 0.625 gram lead oxide and 50 grams of a 30-35 mesh sand are charged to the beaker. The beaker is then placed in a bath or heating block and heated to a temperature of 300 *-2 F.), while the contents are stirred by means of a stirrer rotating at 750 r.p.m. The contents of the beaker are maintained at this temperature for twenty-four hours, after which the copperlead test specimen is removed, rinsed with naphtha, dried and weighed. The test specimen is then replaced in the beaker and an additional 0.375 gram of lead oxide added to the test oil. At the end of an additional twenty-four hours of test operation, the test specimen is again removed, rinsed and dried as before, and weighed. The test specimen is again placed in the beaker together with an additional 0.250 gram of lead oxide and the test continned for another twenty-four hours (seventy-two hours total). At the conclusion of this time, the test specimen is removed from the beaker, rinsed in naphtha, dried and weighed. The loss in weight of the test specimen is recorded after each weighing. A sample of the lubricant under test is withdrawn at the 24, 48, and 72 hours and the acidity of the sample determined.

The following samples were subjected to the above test and the data so obtained are tabulated below.

Sample A-Solvent extracted SAE 30 base mineral oil containing 3.3% of a barium-containing neutralized reaction product of P 8 and a polybutene of about 1000 molecular weight.

Sample B-Sample A +1% of the product of Example I.

Sample C-Samp1e A+1% of the product of Example II.

Sample DfiSample A+0.75% of the product of Example II.

Sample E-Sample A+0.5% of the product of Example H.

Sample F-Sample A+0.75% of the product of Example III.

Same as Sam le A but contained 5.4% of the bariumgortitainlng neutra ized reaction product of Pass and the polyu epe.

6 Sample G-Sample A+0.75% of the product of Example IV.

Sample H-Sample A+1% of the product of Example V. Sample I--Sample A+1% of the product of Example VI.

Table I Acidity, Mg. KOH/gr. Oil Corrosion, Mg. wt.

loss Sample 24 Hrs. 48 Hrs. 72 Hrs. 48 Hrs. 72 Hrs.

Since, in the test, weight losses of 200 milligrams in 48 hours and 500 milligrams in 72 hours are allowable, the effectiveness of the reaction products of the present invention is demonstrated by the above data.

Concentrates of a suitable oil base containing more than 10%, for example, up to 50% or more, of the reaction products of the present invention, alone or in combination with more than 10% of other additives, such as detergent-type additives, can be used for blending with hydrocarbon oils or other oils in the proportions desired for the particular conditions of use to give a finished product containing from about 0.01% to about 10% of said reaction products.

While this invention has been described in connection with the use of the herein described additives and lubricant compositions, its use is not limited thereto but the same can be used in products other than lubricating oils, such as for example, fuel oils, insulating oils, greases, non-drying animal and vegetable oils, waxes, asphalts, etc.

Unless otherwise stated, percentages given herein and in the appended claims are weight percentages.

Although the present invention has been described with reference to specific preferred embodiments thereof, the invention is not to be considered as limited thereto, but includes within its scope such modifications and variations as come within the spirit of the appended claims.

I claim:

1. A new composition of matter, the oil-soluble product obtained by reacting an aldehyde, an alkyl mercaptan and 2-amino-5-thio-1,3,4-dithiazolidine in the molar ratio of from 1:1:1 respectively to 2:221 respectively, said reaction product having corrosion and oxidation inhibiting properties and being suitable for addition to an oil to impart corrosion and oxidation resistant properties thereto.

2. A- compcsition of matter as described in claim 1 in which the aldehyde is an aliphatic aldehyde of from 1 to about 20 carbon atoms.

3. A composition of matter as described in claim 1 in which the aldehyde is an aromatic aldehyde.

4. A composition of matter as described in claim 1 in which the aldehyde is a heterocyclic aldehyde.

5. A composition of matter as described in claim 1 in which the mercaptan is an aliphatic mercaptan.

6. A composition of matter as described in claim 2 in which the aliphatic aldehyde is formaldehyde.

7. A composition of matter as described in claim 2 in which the aliphatic aldehyde is Z-ethyl hexaldehyde.

8. A composition of matter as described in claim 3 in which the aromatic aldehyde is benzaldehyde.

9. A composition of matter as described in claim 4 in which the heterocyclic aldehyde is thiophene Z-carboxaldehyde.

10. A composition of matter as described in claim 5 in which the aliphatic mercaptan is t-octyl mercaptan.

7 11. A composition of matter as described in claim 5 in which the aliphatic mercaptan is t-dodecyl mercaptan. 12. A composition having corrosion and oxidation resistant properties comprising a major proportion of an oil and from about 0.01% to about 10% of'the oil-soluble product obtained by reacting an aldehyde, an alkyl 'mercaptan, and 2-amino-5-thio-l,3,4-dithiazolidine in the molar ratio of from 1:1:1 respectively to 2:221 respectively.

13. A lubricant composition comprising a major proportion of a lubricating oil and from about 0.01% to about 10% of the oil-soluble product obtained by reacting an aldehyde, an alkyl mercaptan, and 2-amino-5- thio-l,3,4-dithiaz olidine in the molar ratio of from 1:1:1 respectively to 2:2:1 respectively. 14. A lubricant composition comprising a major pro portion of a lubricating oil, from about 0.05% to about 25% of a phosphorusand sulfur-containing detergent additive, and from about 0.01% to about 10% of the oil-soluble product obtained by reacting an aldehyde, an alkyl mercaptan, and 2-amino-5-thio-1,3,4-dithiazolidine in the molar ratio of from 1:1:1 respectively to 2:2:1

respectively. 4

15. A lubricant composition as described in claim 14 in which the phosphorus and sulfur-containing detergent lubricant additive is a neutralized reaction product of a phosphorus sulfide and a hydrocarbon.

16. A lubricant composition as described in claim 14 in which the phosphorus and sulfur-containing detergent lubricant additive is an alkaline-earth-containing neutralized reaction product of a phosphorus sulfide and an olefin polymer. 17. A lubricant composition described in claim 14 in which the phosphorus and sulfur-containing detergent lubricant additive is a barium-containing neutralized reaction product of a phosphorus sulfide and an olefin polymer.

18. A concentrate addition agent for lubricant compositions comprising a lubricating oil containing more than 10% of the oil-soluble product obtained by reacting an aldehyde, an alkyl mercaptan, and 2-amino-5-thio-l,3,4- dithiazolidine in the molar ratio of from 1:1:1 respec tively to 2:2:1 respectively, said concentrate being capable of dilution with a lubricating oil to form a homogeneous mixture containing from about 0.01% to about 10% of said reaction product.

References Cited in the file of this patent UNITED STATES PATENTS 2,703,784 Fields Mar. 8, 1955 2,703,785 Roberts et al Mar. 8, 1955 2,749,311 Sabol et a1 June 5, 1956 2,764,593 Harris et a1 Sept. 25, 1956 2,768,999 Hill Oct. 30, 1956 2,783,241 Young et a1 Feb. 26, 1957 2,796,402 Kluge et al. June 18, 1957 2,796,404 Levin June 18, 1957 

1. A NEW COMPOSITION OF MATTER, THE OIL-SOLUBLE PRODUCT OBTAINED BY REACTING AN ALDEHYDE, AN ALKYL MERCAPTAN, AND 2-AMINO-5-THIO-1,3,4-DITHIAZOLIDINE IN THE MOLAR RATIO OF FROM 1:1:1 RESPECTIVELY TO 2:2:1 RESPECTIVELY, SAID REACTION PRODUCT HAVING CORROSION AND OXIDATION INHIBITING PROPERTIES AND BEING SUITABLE FOR ADDITION TO AN OIL TO IMPART CORROSION AND OXIDATION RESISTANT PROPERTIES THERETO. 